No, in that context, "my clothes" can only refer to the type of clothes that Mike typically wears (what you call "his right previous clothes") because at that moment, he's wearing Mary's clothes, not his own clothes, so there's no chance they match.

Now, if the same situation happened, but Mike didn't change his clothes, and continued wearing the clothes he had on during the flight, then "my clothes" would be ambiguous because it's possible that the clothes Mary is wearing match the clothes Mike has on right now.

No, in that context, "my clothes" can only refer to the type of clothes that Mike typically wears (what you call "his right previous clothes") because at that moment, he's wearing Mary's clothes, not his own clothes, so there's no chance the clothes Mary is wearing look like the clothes he has on at that moment.

Now, if the same situation happened, but Mike didn't change his clothes, and continued wearing the clothes he had on during the flight, then "my clothes" would be ambiguous because it's possible that the clothes Mary is wearing match the clothes Mike has on right now as they're both his clothes.